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Feb'. 12, 1929. 1,7011730 c. H RorH Er AL SYSTEM OF CONTROL FOR ELECTRIC ELEVATOR EQUIPMENT Filed Sept. '6. 1924 C ILIITISIIF z/e/z Alors: wm, A CVM/@L56 H. @0TH l NQ/QT/NCH/FF m @m m Patented Feb. 12, 1929.

UNITED stars...

morne sereni* ortica.

i CHAR-LES E. ROTH AND MARTIN SCHIFF, OF CHICAGO, ILLINOIS, ASSIGNORTO ROTH BROTHERS & CO., 0F CHICAGO, ILLINOIS, A CORPORATC'N OF ILLINOIS.

`SYSTEM GF CONTROL EUR ELECTRC-ELEVATOR EQUPMENT.

Application filed September 6. 1824. Serial No. 736,369.

The main objects of this invention are to provide, for high speed passenger elevator service ot the motor-generater-motor typ l a cou'iter electroniotive controlling device t'or the regulation of speed and smoothness ot op- Lion; to provide a counter E. -h l?. generated by a rotating member in which the amount of E. M. l". and the direct' n ot current is controlled in part manu part automatically'to meet Vthe r of service; to provide a controller-exciter with a simple field regulator which tai e place of the usual elaborate elect elevator control; to provide a controller-exciter which will automatically maintain a constantmotor speed inboth directions substantially y.independent of load.

Past practice hasV required an elaborate system of controlling devices to properly regulate the speed and reverse the elevator motor with a reasonable degree ot smoothness ot operation. Renement in elevator motor controlling has tended toward complicated devices and attachments to prevent jerky stops and starts and to provide smooth acceleration and deceleration. The motorgenerator-motor system of elevator control is one in which the elevator motor is supplied With current from a generator driven by another motor, and these three machines comprise the principal units. Sometimes a second generatoroif small size is used for Jfurnishing current to excite the iields ot both the elevator motor and oi the main generator. n

Our improvements in elevator motor control comprise the substitution of simple iield regulating rheostat and a small 5 r atorfor the complicated controlling deHcer-i which have becnused in the motor-generator-motor sets.

The elevator motor proper is preferably oit' the type that normally operates with a full iield and the speed variation is obtained by varying the armature voltage. lts actual operating speed, therefore, may be any speed between zero and the maximum in either direction, the maximumspecd ot the motor being its normal rating. The varia` tion in speed ot the elevatorl motor is obtained by having its held separately excited at a constant value of one polarity, ano applying to thearmat-ure of the elevator motor a voltage Whose value varies in exceedingly minute steps from zero to maximum and back to Zero in either positive or negative direction,

the travel of the elevator requires. The currentfurnished to the elev ator motor supplied by a generator ot' similar voltage and current chiaracteristicsI as the elevator motor. This generator has a separately excited i'ield which is reversible in polarity, thereby generating current in the armature ot the generator in either direction, Which current in turn drives the elevator motor forward or backward. The armature of the elevator motor and the armature of the generator may be permanenth7 connected electrically. The generator is driven by a constant speed motor o'y erating from any suitable alternating or dii y,t curl rent circuiti Exciting current ot' a constant value for the elevator motor field, for the bralre coils (not shown), for auxilliary controlapparatus (not shown), and tor one polarity ot the exciting` current for the ofen erator field, is furnished by a small exciter generator of suitable capacity and vct and a low capacity floating storage liz Gur invention comprises di). e us'.x orp a system in which a second exciter generator or controller-exciter is used, Whose armature is electrically connected in series with the iii-st er. ter arn'iature, the action ot which is disclosed in the following diagrammatic circuit draivings, in which Fig. l shows a motor-genera with a separate exciter and a controller-exciter, 'valli tlA niter neutralizing tl tor iicld circui A Fig. 2 shows a motor-generatior-motor set Witi the control in such position that thc he current 3 shows the motor-generatorsnotor i the control in such position that the lim-exciter produces substantially no age and the generator fiele is excited by current from the regular exciter.

`ig. i a drivi. motor M direct-drives a genera troller-ex i machine furnishing' current to its own field coil l, and is directly connected to the ticld coil 2 ot the elevator motor E and a r'loating storage battery S. The field of the generator is magnetized by the ticleL coil 3, current being supplied by leads from the eX- citer-generator ln series With the field coil 3 ot the generator is the armature ot the controller-excite B. In `parallel `with the fieldcoil 3 of the generator and armature of controller-exciter, is the fieldcoil 4 of the controller-exciter, and the control rheostat .5, with a manually operated rheostat handle A.

In the 'circuit 6 connecting of the generator and elevator motor is a series field coil 7, forming-a part oft the field Winding of the controller-exciter B by its passage around. the field cores thereof.

In Fig.V l, the exciter X is rated to deliver 115 volts, andA the rheostat handle A. is positioned so that the coil 4l ot the controller-exciter will receive aiprexirnately 57% volts. The Winding and speed of the armature of the controller exciter B is such that in that particular position of said rheo- .stat the controller-exciter Will generate the sanie voltage as the regulator exciter X, but of opposite polarity, so that no current will flow through the generator field coil 3 because the counter or bucking Edi/I, l?. of the controller-exciter will exactly equal-that oi' the regular exciter, vand the Vresult Will be a zero current in the field coil ofthe generator, anda Zero current inthe ent-ire generator elevator circuit 6.

In Fig. 2, with exactly the same arrangement, except that the controllerk handle A cuts out all of theresistance, the controllerexciter generates more voltage than the regular exciter, and the resulting current through the iield coil 3 is furnished' by the controller-exciter, Since thev current generated bythe controller-exciter is opposite in direction to that of the regular exciter X,

the current between the generator and the elevator motor will be ina direction opposite to what it Would'be it the regular exciter were furnishing thev current. to inagnetize the generator field 3.

In Fig. 3, the rheostat handle A is so positioned at'the extreme end of the resistance coil 5, that substantiallj,7 no currentpasses through the lield coilll. In this position current Will flow through the controller-exciter arinature Without hindrance, and the generator fields Will be inagnetized in substantially the same manner as though the controller-exciter did not exist.

In the position of the rheostat handlei, as shown in Figi, no current flows in circuit 6 between the generator and the elevator motor. I-Ience, the elevator niotor would stand-still. l i

In Fig. 2 the generator field is excited by current furnished by the controller-exciter, giving current between theV generator and the elevator motor over the circuit-6 at full strength in one direction. Y

In Fig. 3 the controller-exciteris not'generating current, and hence the generator field 3V is excited' by the regular exciter X, and' current Will flowat full strength from the armature the generator to the elevator motor over the circuit 6 in the opposite direction from that shown in Fig. 2. v The circuit 6 is carried through the series coil. 7 ot the controller-exciterand is so connectedthat the magnetism produced by thecoil rrivill assist the coill 4i under norinal operation, but Will oppose the `function of coil 4e due to reversal of current in circuit 6 When the elevator niotor tends to exceed its norinal speed, the result being that as the controller-exciter begins to counteract the regular exciter X, the field coil 3 ot the generator becoines weaker, causing the generator, new acting-as a motor, to speed up, and causing the niain ino-tor to now act as a generator, thereby putting a load on the Inain motor (acting as agenerator), Whereby the entire system Will quickly reach a point of stabilityWherel the differencesin the elevator speeds under varyingfconditions ot load are nearly zero. It, While being normally operated, the field coil 3 should becorne disconnected, the armature of main generator G would be a non-opposing or short path torcurrent generatedby theelevator inotor armature causing d'ynainic braking thereby bringing; the eleva-tor inotor to a stop. Y

In operation, the use ofthe controllerexciter'B Whose'arniature is electrically connected-in series with the regula-r exciter X,

performs onev of the three following Jfunctions: Y

lst-Io furnish zero voltage,- thereby allowing the regular exciter to 1furnish full current to the ield coils 3 ofthe inaingenerator;

2nd- To generate voltage equal-to that oft the exciter X, but opposing.thefvoltage oi the exciter X, neutralizing the entire circuit to the point Where no current flows through the inain generator ield circuit 3. This action is substantially equivalent to an open circuit, yet at no point in the operationis there an open circuit;

3rd- To generate twice the voltage of the exciter X, thereby opposing the lvoltage of the exciter and furnishing to the field or' the niain generator current ot equal value but of opposite polarity to that furnished by the exciter X. When the controller-exciteil gives Zero voltage.

The controller-exciter Bfinay be called va Y buckino exciter because it opposes the current or' the regular exciter. f The field of the controller-exciter is energized by the regular exciter X. The regular exciter and the controller-exciter can both be driven by the inotorthat drives the rnain generator, lor Vthey can-be separately operated by any otherpoiver. anisinin the elevator, Aand other electroreceptivek devices and auxiliary switches for safety in operation as Willbe` understood,

The brake inechy though notshown. may be operated by current furnished by the regular exciter. However, the varying voltage of the controllerexcitervmay also be used to operate lock-out or other devices (not shown) until the proper time for them to function.

Considering the system in its simplest form, its operation would be as follows:

The controller arm would be in the neutral position, as shown in Fig. l. The main motor M would be started, driving` the main generator G, the exciter X, and the con troller-exciter B. The exciter X will build up its own voltage, excite its own i'ield, excite the field ot the elevator motor E, and excite the shunt field of the controller-exciter B to a point where the exciter X and the controller exciter B generate equal voltages, but opposed to each other. Under this condition, no current will flow in the circuit between the generator G and the elevator motor E. Y

lVhen the operator moves tie controller arm A for the up direction of the elevator, the connectionsand positions are as shown in Fig. 2, in which the controllerk arm A has been moved to reduce and finally cut out all resistance in the field circuit of the controller exciter B, thereby raising the voltage ot B, which, overcoming the voltage ot the regular exciter X, increases the lield strength of the generator G, the voltage ot the armature G, and the speed of the elevator motor E. Fig. represents the position of the control for the full speed of the elevator going up.

Fig. 3 represents the positions of control and the direction of the current for full speed of the elevator going down.

To move from the position of full speed up to full speed down, the operator reverses the controller arm A from the position shown in Fig. 2 to that shown in Fig. 3. The operation ot reversal comprises tirstl Igetting to the neutral or central position of: the controller arm A, which gives the same voltage to the controller-exciter B and the regular exciter X, which results in no field current for the generator' and nov current flowing between the generator and the elevator motor. Further movement of the controller arm in a down travel direction gradually reduces the iield strength of the exciter-controller and the voltage ot its armature, allowing the regular exciter X to furnish current to the fieldv in the proper direction for down travel. A complete reversal of current in the lield coils of the generator taires place without opening any electrical circuits.

. Experience has proven in operating electrical elevators, that a condition arises when the elevator is heavily loaded for down travel where a loaded car tends to drive the elevator motor E as a generator, this in turn driving the generator as a motor, andthe main motor as a generator, a condition wl ch represents a. complete reversal of operation oic all three machines. This action should of itself stabilize the speed of the system. Due, however, to voltage losses in the various circuits that carry the driving currents, there is a tendency for the elevator motor to gain considerable speed before being checked by the iinal load delivery back to the power lines.

To overcome this tendencv, the circuit between the generator and the elevator motor is carried around 'the field o1" the controller exciter so that the main current between the f'enerator and the elevator motor strengthens the fields ot the controller exciter under normal operation, but will decrease this iield when the elevator tends to exceed its normal speed, the result being that the controller'- exciter now begins to counteract the regular exciter the field of the generator becomes weaker, causing the generator, which under overhaul conditions, acts as a motor, to speed up, causing the main motor, now acting as a generator, to load itself by pumping current into the power mains, and to quickly reach a point of sta-bility where the ditierences in the elevator speeds under varying conditions of load are substantially zero.

The provision ot a low capacity accumulator designed to float on the exciter circuit substantially insures sufficient current to excite the fields of the elevator motor even in case of the complete failure of the driving motor M. The energized held of the elevator motor would, in the event of an overhaul load on the elevator, prevent acceleration due to the short circuit effect oi' the generator armature.

Although but one specific ambodiment ot' this invention has been herein shown and described, it will be umlerstood that numerous details ot the construction shown may be altered or omitted without departing i'roin the spirit of this invention as delined by the following claims.

lVe claim:

l. An elevator drive and control system comprising, in combination, a motor, a niechanically driven generator electrically connected in series therewith, said generator having a iield coil, a constant voltage exciter to which said coil is connected, said motor having a field coil constantly energized by said exciter, a constantly driven controller-exciter electrically connected in series with the iield coil of said generator' and said exciter and having a field coil energized by said exciter, and means for regulating the energization of said controller exciter tield coil, said generator, exciter and controller-exciter being mechanically connected.

2. In `an elevator system a inotor, an .eX- `citer to energize the field of said motor, a -jg'eneratorto furnish eur-rent for the `arma- .tureAo-eaid motor, field exciting current for Saidigeneratorbeing Supplied 'from said eX- r"Citer, a controller-exciter lhaving its armature in series Withthe ield coil ot said genierator, areld e011 -or .said controller-exciter in Aseries with the main .generator elevator motor' circuit and a ffield @oil :for saidcontroller-exeiter taking current from said eX- citerV9 -a rheostat -in the .latter ysaid vfield coil Circuit, said rheostat being ladapted to manuallyeontrolvthe direction and amount of eurrent'supplied-to,theeaidgenera 4or by Asaid oontrollereXeiter.

3. :Foreleva-tor service-Van elevator motor, adriven generator furnishin` current tothe armature fof:saidelevator'finotor, an exciter magnetizing thev fields of both Said felevator motor and said generator, 'a rotating eentroller-exeiter with its armature in series with the generator `tleldeireuit Iand ycon-trol- Y August, 1924:.

.ling rthe .direction fandlmagnitude of 'the ,curl yrent throng-heard generator ieldfeircuit, and

means providing' a magnetizing current Aand :forming part of the ,ield Control for said controller exciter, connected V1n series With the generator ,armature and elevator motor.

4. In combination, ,a niotor, a generator .connected in .series with the motor, a field exciter, and a. controller eXciterQ, said genera-V tor having- -a ield coil connected in Series .with `the afield exciter ,and the controller ,exy CHARLES RCT-H.

, Signed l,at Chicago this 25th .da7V ot August, 1924.

d MARTIN SCHIIF; 

